Homes, offices, warehouses, and other buildings are in constant need of more storage space. Areas within the buildings—closets, cupboards, attics, shelves, and the like—are often set apart for this purpose, but these storage spaces are seldom used efficiently or to full capacity. Even when the spaces are used to full capacity, maintaining order and accessibility presents a further challenge. Accordingly, various storage systems have been designed to improve the efficiency, accessibility, and organization of various storage spaces.
One such storage system design is an automated storage and retrieval system. An automated storage and retrieval system allows a user to select a desired item or set of items and instruct that the items be brought by mechanical means from distant storage areas to a convenient access point. Thus, automated storage and retrieval systems provide a convenient method for locating and accessing goods while utilizing space that would otherwise be difficult to access.
A wide variety of automated storage and retrieval systems exist in the prior art. Larger scale systems—for example, those used in a warehouse setting—use a variety of automated conveyor belt and/or transport vehicle devices to store and retrieve items. In such cases, items are stacked in multiple layers and space is allotted on at least one side of each stack to access and remove an item at any location within the stack. In smaller scale settings, storage and retrieval systems have been designed that rearrange stored items within a stack until a desired item is accessible at a designated access point.
One example of the latter is a revolving carousel. In the carousel, items are rearranged by moving around a circular track, allowing each item to pass through an access point in turn. This requires less space than the larger scale systems described above; however, this design is still not the most efficient given that space must still be allotted on each circular portion of the track to allow items to pass by each other.
An improvement on the revolving carousel optimizes space by moving items only linearly. In such a method, repeatedly moving one item horizontally from either the top or bottom of a stack and then moving all of the items remaining in the stack vertically to fill the vacant space, creates a circular motion, such that a desired box eventually reaches an access point. Certain embodiments utilize tracks and wheels or conveyors for horizontal movement and lifts for vertical movement. While this linear movement method has a smaller space requirement than the carousel, current embodiments still have several disadvantages.
One disadvantage is that each column of items is supported by the bottom item, which requires that each item in the column be able to bear the weight of all items above it. This places structural requirements on each item that increase costs and waste space. Another disadvantage is that the system can only function if it is at full capacity (meaning it has exactly one vacancy). Furthermore, while the system is not limited to only two columns of items, due to the rotational motion and the nature of the actuators that enable it, any additional column could only accommodate two items, one at the top and one at the bottom. Finally, a disadvantage is that an item must pass through the full rotation before it can be accessed, rather than allowing often-used items to maintain positions of easy access, while seldom-used items maintain distant positions.
In light of the foregoing, what is needed is an automated storage and retrieval system that utilizes linear movement, but that improves on these disadvantages.